Aerodynamic engine system

ABSTRACT

A lift-fan engine system of small size but strong lifting power which comprises a lift-fan having a plurality of fan blades each formed by an inner-fan blade portion gradually twisted toward its outside and a turbo-fan blade portion incorporated with the inner-fan blade portion at its outer end. At the boundary between the inner-fan and turbo-fan blade portions is provided a first shroud segment of the turbo-fan blade portion and beneath it is provided a second shroud segment. By radially mounting the fan blades as constructed in the above by means of their root portions on a fan or rotor disc, the first and second shroud segment of the respective fan blades are adjoined with the first and second shroud segments of adjacent fan blades so as to constitute a first ring and a second ring between which a passage of the high-temperature gas is formed.

United States Patent [191 Kawamura AERODYNAMIC ENGINE SYSTEM Osamu Kawamura, No; 2-13 Koganehara, Matsudo, Japan [22] Filed: Mar. 29, 1972 [21] Appl. No.: 239,113

[76] Inventor:

[52] US. Cl 60/226 R, 60/269, 60/39.'43, 244/23 B, 417/355 Int. Cl. F02k 3/04 Field of Search 60/226 R, 269, 39.43;

References Cited UNITED STATES PATENTS 6/1960' Howell 60/226R 1-0/1962- Griffith' 60 226 R 4/1963 Irbitis 60/226 R 9/1966 Borysthen....- 60/269 3,496,725 2 1970 Ferri 607269 3,603,082 9 1971 Sneeden 60/226 R FOREIGN PATENTS OR APPLICATIONS 1,002,462 8/1965 Great Britain 60/226 R 1,297,540 5/1962 France 417/355 Jan. 8, 1974 Primary ExaminerDouglas Hart [57 ABSTRACT A lift-fan engine system of small size but strong lifting power which comprises a lift-fan having a plurality of fan blades each formed by an inner-fan blade portion gradually twisted toward its outside and a turbo-fan blade portion incorporated with the inner-fan blade portion at its outer end. At the boundary between the inner-fan and turbo-fan blade portions is provided a first shroud segment of the turbo-fan blade portion and beneath it is provided a second shroud segment.

By radially mounting the fan blades as constructed in 7 Claims, 18 Drawing Figures- PATENTEB JAN 74 SHEET 1 BF 5 FIG] PATENTEI] JAN 8 sum 2 0r 5 PMEMEB JAN 8 i974 SHEEI 3 [IF 5 1 AERODYNAMIC ENGINE SYSTEM head portion, etc. of the aircraft in vertically fixed or movable manner.

It is known that engine systems employing a lift fan are most preferable in practical use because they have an advantage to render the rate of fuel consumption very lower.

Generally, the lift fan engine is installed in a manner such that it can rotate about a vertical axis in a circular opening formed vertically in a suitable portion of the main wing whereas the lift fan comprises integrally a plurality of turbine blade portions at its outer periphery and is driven to rotate by the exhaust gas from the main engine.

However, such prior art lift-fan engines have disadvantages such that structure of the turbine blade incorporated at the outer periphery of the fan is complicated and that in order to drive the turbine blades of such a incorporated structure a long and large duct must be provided in heat insulated form which enables gas of high temperature to flow, resulting in an increase of weight.

Moreover, due to its uniqueness of structure, etc. the lift fan engine has poor stability of operation and control during flight, and consequently it is still unavailable for civil aircrafts.

Under these circumstances, the inventor has studied for purposes of obtaining a lift fan engine which not only has lightweight, simple and compact structure, but also provides high lifting power or thrust and is easy in control and operation, and then has found that said 'disadvantages can be eliminated by improving the construction of the lift fan and'its driving system.

Accordingly, a general purpose of the invention is to provide a widely usable lift-fan engine system which not only is lightweight and small in occupying space but also produces strong lifting power.

In accordance with the invention, the exhaust gas of a turbo jet engine, the bleed air of a bypass jet (a fan jet) or a turbo jet, or mixture of the exhaust gas and the bleed air is supplied to a combustion chamber through a valve, and is burned to change into gas of high temperature by a burner to an extent in which most of the oxygen contained therein is consumed. Then, said hightemperature gas is guided through a scroll to a nozzle directed to turbo-fan blade portions integral with airguide or inner-fan blade portions of the lift fan, and consequently is blown toward fractional portion of the periphery of the lift fan to provide thrust.

That is, the principal object of the invention is to provide a lift-fan engine system comprising a lift fan assembly having a plurality of fan blades arranged radially each consisting of an incorporated turbo-fan blade portion and inner-fan blade portion, burner means for producing high-temperature gas by burning bleed air, exhaust gas or their mixture, nozzle device located adjacent to said burner means for supplying said hightemperature to a predetermined circumsferential portion of the lift fan at high pressure.

With the above-mentioned construction of the liftfan engine system according to the invention, the nozzle device and the lift fan are placed adjacently each other so that nozzle portion of the nozzle device and the fan blades of the lift fan may be degraded by heat- Therefore, another object of the invention is to provide a lift-fan engine system in which the nozzle device and the lift fan assembly can be cooled sufficiently.

A further object of the invention is to provide a liftfan engine system wherein a nozzle device for blowing high-temperature gas comprises one or more nozzle means and their nozzle apertures are directed to a restricted peripheral portion of the lift fan. With this construction-the high-temperature gas is applied only to a fractional outerportion of the lift fan during its rotation while the remaining portion of the lift fan is cooled upon rotation.

Another object of the invention is to provide a lift-fan engine systemwith which nozzle members of the nozzle device are provided with cooling means by forming a plurality of passages for cooling medium inside of each nozzle member.

. Furthermore, an important object of the invention is to provide a lift-fan engine system which is small-sized and can produce a strong lift. To this end, the lift-fan engine system comprises a lift-fan having a plurality of fan blades each formed by an inner-fan blade portion gradually twisted toward its outside and a turbo-fan blade portion incorporated with the inner-fan blade portion at itsouter end. At the boundary between the inner-fan and turbo-fan blade portions is provided a first shroud segment of the turbo-fan blade portion and beneath it is provided a second shroud segment. By radially mounting the fan blades as constructed in the;

structed in an integral form by incorporating both the turbo-fan and inner-fan blade portions, so that its manufacture is facilitated. Since the lift fan is blown partially by the high-temperature gas whereas its remaining portion is cooled upon rotation special metallic materials which are very expensive and have higher heatresistant property are not needed. Thus, according to the lift-fan engine system of the invention, reduction in cost, weight and dimensions is achieved.

Still a further object of the invention is to provide V/STOL aircrafts provided with the lift-fan engine system as mentioned above.

Another objects, features and advantages of the invention will be apparent from .the following description in connection with the accompanying drawing in which:

FIG. 1 is a sectional view of a lift-fan engine system according to the invention;

FIG. 2 is a partially removed a plan view of the liftfan engine system shown in FIG. 1;

FIG. 3 is a sectional view in an enlarged scale of the lift-fan engine system shown in FIG. 1;

FIGS. 4, 5, 6 and 7 are sectional views of a fan blade taken along lines IVIV, VV, VI-VI and VII-VII of FIG. 3, with which twisted angle at various portions of the fan blade are illustrated with respect to the fan blade root respectively;

FIG. 8 is a perspective view of a fan blade which constitutes the lift fan;

FIG. 9 shows an example of an aircraft in perspective view which is provided with the lift-fan engine system of the invention in wing;

FIG. 10 is a plan view of the engine system of FIG. 9 in an enlarged scale;

FIG. 11 is a sectional view of a regulating device for output power of the main engine;

FIG. 12 is an enlarged sectional view of essential parts of FIG. 11;

FIGS. 13, 14 and 15 show schematically various system for driving the lift-fan engine system, respectively;

FIG. 16 is a sectional view illustrating another example of an aerodynamic engine to which the lift fan de vice of the invention is applied;

FIG. 17 shows a sectional view of an example of an aerodynamic engine combined with the lift fan device; and

FIG. 18 is a partial side section of an embodiment in which a guide vane is placed in front of the lift fan unit.

Referring to FIGS. 1 and 2, a lift-fan engine of the invention for use in system constructed as shown is operated so that exhaust gas, bleed air or their mixture obtained from the main engine (not shown) is introduced to a combustion chamber 10 and is burned in a wellknown combustor 12 to such an extent that most of oxygen contained therein is consumed, the resulting gas of high temperature being guided to nozzle means 16 through a scroll 14 and being blown from the nozzle means 16 towards a restricted outer peripheral portion of a lift fan 18 to drive the latter in-the direction as indicated by the arrow in FIG. 2 while simultaneously a large amount of air being introduced from an air intake to an inner-fan blade assembly of the lift fan 18 and the resulting air flow being blown off downwardly through a diffuser guide vane 20 to obtain thrust.

The nozzle means 16 is arranged adjacently along the restricted outer periphery of the lift fan 18. The nozzle I means 16 comprises a plurality of nozzle-guide vanes 22, each of which is provided with a plurality of hollow passages 24 to pass fuel oil (before supplying the combusion chamber) therethrough so that each nozzle guide vanes 22 is cooled so as to be heat resistant while efficiency of combustion can be increased by feeding the preheated fuel oil serving as coolant to the combustor 12. Wall portions of the combustion chamber 10 and the scroll 14 are cooled by known air or liquid cooling methods and the combustor 12 used has wall portions of conventional cooling structure. It should be noted that the combustor 12 extends up to the inside of the scroll l4 and is disposed near the inlet side of the exhaust gas of the nozzle means 16 so that lifting power of the gas from the nozzle means 16 can be increased.

The lift fan 18 of the invention as shown in FIGS. 1 and 2 comprises a plurality of fan blades 32 each consisting of a turbo-fan blade portion 28 and an inner-fan blade portion 30 which are manufactured in a single body by molding light-weight and heat-resistant alloy such as titanium series alloy or stainless steel andthe like. The lift fan 18 is completed by radially mounting a number of said fan blades 32 around a fan disc 36 journalled on a shaft 34 (FIG. 1 Each of the turbo-fan blade portions 28 which constitute the outer periphery of the lift fan 18 is divided at its tip end into two parts via a small notch so that one of them forms a nozzle exhaust-gas guiding fin member 40 and the other forms an auxiliary fin member 42. An outer end of the nozzle exhaust-gas guiding fin member 40 is inserted slightly into the outlet of the nozzle means 16. A pair of substantially triangle-shaped outer shroud segments 46 and 47 are provided symmetrically on both surfaces of the fan blade 32 at the boundary of the inner-fan blade portion 30 and the guiding fin member 40 of the turbofan blade portion 28, and similarly a pair of substantially triangle-shaped inner shroud segments 44 and 45 are provided in a symmetrical form on the both surfaces of the fan blade 32 at the crossing portion of the exhaust-gas guiding member 40 and the auxiliary fin member 42. The fan blades 32 thus constructed are arranged radially through their root portions on the fan disc 36 (FIG. 1) so that the outer shroud segments 44 and 45 forms an outer separation ring 48 by connecting the respective adjacent shroud segments each other and the inner shroud segments 46 and 47 constitute an inner separation ring 50 by joining the adjacent shroud segments to one another. As a result, a passage 52 for gas of high temperature is formed between the outer and inner separation rings 48 and 50. The inner shroud segments 46 and 47 forming the inner separation ring 50 serve to reduce flow loss and turbulent loss of the high-temperature gas in the lift fan, while the auxiliary fin members 42 act to prevent vibration of the fan blade 32 and hence the lift fan 18. In addition, the upper side of the turbo-fan blade portions of the lift fan 18 facing the nozzle aperture is provided with a turbine cover 54 which is cooled by fuel oil or air from the outside since the cover 54 is heated directly by the hightemperature gas. On the other hand, the remaining peripheral portion which is not covered by the cover 54 is surrounded by an outer casing 55.

The fan blade 32 used in the lift fan of the inventionis formed so that it is gradually twisted from its root of christmas-tree type 56 to the outer end (FIGS. 4-6).

The above-mentioned structure of the lift fan 18 not only facilitates manufacturing of the latter and reduces its weight but also dispenses with a conventional ring to connect each turbine blade. Thus, for the lift fan of a given radius, a larger amount of air flow and higher thrust can be obtained from the lift fan system in the same dimensions, and its lifting power can be controlled quickly and exactly by increase or decrease of injecting the amount of fuel in the combustion chamber 10. Upon rotation of the lift fan 18, some of the turbofan blade portions 28 are driven as turbine and heated at a restricted peripheral portion of the lift fan by the exhaust gas from the nozzle 16, while the rest of the turbo-fan blade portions 28 running through the remaining peripheral portion of the lift fan is exposed to air and serves asair quiding blade portions. Accordingly, the turbo-fan blade portions 28 which are guiding air are cooled by air at that period, so that the lift fan itself can be held at lower temperature even under such condition that the temperature of the exhaust gas from the nozzle 16 is considerably high.

The lift fan assembly 18 is formed as a whole in a shape of flat and thin disc, so that it can be installed in wing of aircrafts. In this respect the lift fan according to the invention is applicable to aircrafts of various types because the lift fan in-wing provides smaller air resistance during high-speed cruising due to its small front area.

FIGS. 9 and 10 show an example of an aircraft provided with the lift fan system of theinvention in a manner such that two set of paired lift fan units 59 are installed symmetrically near the fuselage in the right and left wings 58, respectively. Upon operation of these lift fan units 59, two main jet engines of bypass type 60 are utilized as gas generators, and bleed air obtained from each main jet engine is supplied to the respective paired lift fan units 59 through suitably connected pipes. According to this arrangement, even if one of the main jet engines 60 becomes out of control the other jet engine enables the lift fan units 59 to continue their normal operation. In this embodiment, one common combustion chamber 10 is provided for each-pair of the lift fan units 59, so that the lift fan assembly can be accommodated in wing in compact form.

The aircraft provided with the lift fan units of the invention has various advantages that control of lift can easily be acheived by adjusting an amount of fuel to be supplied into the combustion chamber 10 as explained hereinafter; that in comparison with prior art V/STOL systems, control by the aid of louvers, etc. is not necessary and response characteristics of the system of the invention are improved greatly; and that ducts to be exposed to high temperature are reduced and the nozzle device is decreased in dimensions, thereby enabling production of the V/STOL system in small-size and light-weight.

In this embodiment two set of paired lift fan units are arranged in the right and left wings, respectively, so that the paired lift fans rotate in opposite directions each other to counteract inertial resistance and characteristic of flow passage and thus to prevent pitch, roll and/or yaw of the airframe aircraft.

Upon actual operation of the aircraft according to this embodiment,-use of a regulating device 62 for lifting power of plug-type as shown in FIGS. 11 and 12 is preferred to introduce the bleed air from the main engine 60 to the lift fan 18. The lifting power regulator 62 also serves as valve means which permits part of the bleed air of the main engine 60 to introduce to a bypass duct 64, and comprises-a rear exhaust slot 66 for cruise and a guide opening 68. The exhaust slot 66 is provided with a plug member 70 journalled on a plug shaft 72 to open or close for'adjusting the flow rate of air and with a sleeve valve 74 fitted to the plug shaft 72. By means of a hydraulically or pneumatically operated cam device 76 the plug shaft 72 is caused to move forwardly or backwardly for adjusting the flow rate of air to be introduced to the lift fan 18.

Accordingly, upon vertical take-off or landing of the aircraft, the exhaust slot 66 is closed completely while during transition between vertical and horizontal flight the plug 70 is gradually moved to the left (FIGS. 11 and 12) so that the aircraft can change its flying state to cruising one with high stability.

For driving the lift fan unit according to the invention the following three manners are available in connection with the main engine:

1. as shown in FIG. 13 the exhaust gas of the main engine is introduced to the combustion chamber 10 via valve means 80 which serves also as a lifting power regulating device so that the lift fan 18 is driven to rotate;

2. as illustrated in FIG. 14, the bleed air of the main engine 78 is introduced to the combustion chamber 10 through valve means 80 similar to the above so as to drive and rotate the lift fan 18. In this case, however,

5 a lifting power adjusting device 82 of variable flow type or flow switching type must be provided at-the exhaust side of the main engine 78 so that a thrust in the direction of cruise upon hovering is suppressed; and

3. as represented in FIG. 15, the mixture of the exhaust gas and the bleed air of the main engine 78 is guided to the combustion chamber 10 by mixing them through valve means 80 similar tothe above in order to drive and rotate the lift fan 18.

In the embodiments mentioned above the lift fan has been located in wing near the fuselage. However, it is obvious to one skilled in the art that the lift fan system according to the invention can be installed in suitable manner at any desired position in wing, or the head or tail portion of the fuselage, etc.

FIGS.:16 and 17 illustrate two embodiments wherein the lift fan system according to the invention is utilized in the form of an independent turbine engine. In the embodimentshown in FIG. 16 the fan itself is driven to rotate via bevel gear means 84 connected to a smallsized air compressor 86 from which the compressed air is supplied to the combustion chamber 88. In this case, air is introduced directly from the opening of the compressor 86, so that upon starting the lift fan, rotation must be initiated by feeding air from another smallsized gas-turbine starter, or by the aid of starting means 89 such as electric motor, air turbine, hydraulic motor and the like. Under the above situation it is preferred to insert a ratchet mechanism at junction of the bevel gear.

On the other hand, FIG. 17 shows an embodiment of a composite engine to which the lift fan unit according to the invention is applied. In this embodiment the fan 18 and a multistage compressor 90 arranged coaxially therewith are driven so that the air introduced by the is supplied to a rear combustion chamber 92 and another part of the compressed air is guided to a reverse combustion chamber 94 the exhaust gas of which is caused to circulate to the'fan 18 for increasingly driving its rotation, and moreover the exhaust gas thus produced is after-burned in the rear combustion chamber 92, resulting in jet stream with high temperature and high thrust power. By a variable nozzle 95 provided at the exist of the rear combustion chamber 92, adjustment of fuel and hence thrust can be effected. With this construction a jet engine of after burner type in low cost is available and its starting can be achieved by the various starter means as mentioned above.

FIG. 18 shows an embodiment wherein an air guiding vane 96 is provided in front of the fan-blade portions 32 of the lift fan unit 18. This air guiding vane 96 renders introduction of air smooth even if an angle of entering air varies upon transition of flight, etc., and the thin form.

fan is compressed, and then part of the compressed air whole of lift fan assembly can be constructed in very advance with light weight and low cost. In conventional aircrafts, thrust necessary during take-off is about several tenth of that during cruise, while V/STOL aircrafts need lifting power of the engine upon taking off which is several times that of crusing of usual aircrafts in type of take-off and landing by running. Therefore, when the engine for the conventional aircrafts is used for the V/STOL function, it becomes undesirably large in volume and produces excessive power of exhaust during cruise, which means that the engine is operated in very inefficient manner. Further, since the gas turbine, in general, has low efficiency in partial load condition, long time operation of the gas turbine under not-full load condition results in an inefficient lift fan engine. In contrast thereto, the lift fan engine according to the invention utilizes the bleed air, exhaust gas or their mixture of the cruising engine at maximum temperature so as to increase the lift and/or thrust of the lift fan to values which are several times larger than usual. Thus, the lift fan engine can be designed in harmony with a desired (minimum) thrust upon cruise, so that reduction in rate of air and hence an increase of specific output can be accomplished with economical advantages.

Since the lift fan of the invention can also operate as a free-turbine and is not coupled mechanically with a separate gas generator, etc., only a gas generator is sufficient to provide as accessories including starter, fuel supply device, governer and the like, thereby enabling reduction in cost and improvement of reliability of the engine system.

Rotating speed of the lift fan according to the invention can be controlled only by adjusting an amount of fuel oil and air or gas to be introduced to the combustion chamber, and this adjustment can be effected instantaneously. As a result of omission of various accessories as mentioned above, the lift fan system of the invention provides advantage that the front area of an aircraft installed it is decreased.

It is considered for the lift fan engine of the invention that it is most advantageous when used in air-bleed manner. In this case, light alloy such as aluminum can be used for major parts of the valve, duct, casing of the lift fan, etc., while only parts of the combustor, nozzle, turbine casing, fan disc, and lift fan are needed to be made of suitable heat-resistant materials. Thus, the light-weight lift fan engine for use in an aircraft can easily be obtained.

Upon operation of the lift fan engine of te invention as a turbine, burning gas Of very high temperature is used as mentioned before, however, the nozzle device is disposed merely around a fractional periphery of the lift fan, so that upon its one rotation the turbo-fan blade portions of the lift fan are cooled through a large amount of air at ambient temperature introduced immediately after exposed to the high-temperature gas injected from the nozzle. This operating cycle is repeated about one thousand times per minute, so that in accordance with the lift fan of the invention damage of the turbo-fan blade portion due to heating is minimized. Moreover, use of both the turbo-fan and innerfan blade portions of incorporated form each other permits gas to be applied at maximum temperature with slight degradation in efficiency of the turbine resulting in maximum specific output. Consequently, the lifting power or thrust which is obtained per air contained in compressed unit bleed air becomes maximum and also an increasing rate of the exhausting power required for hovering during several minutes is very high, whereby the desired objects can easily be achieved.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention. For example, the fan blade used in the lift fan of the invention may be replaced by a shaft so that the lift-fan engine of the invention is serviceable as a blowing engine.

What is claimed is:

1. An aerodynamic engine system comprising a lift fan assembly having a rotatable disc, a plurality of fan blades, each constituted of an inner fan blade portion and an integral outer turbo-fan blade portion, said plurality of blades being connected at their inner ends to said disc and being radially outwardly directed therefrom, each of said fan blades being gradually twisted from its inner to its outer end and being provided with a notch in the turbo-fan blade portion for forming a nozzle exhaust-gas guiding fin member and an auxiliary fin member, a set of first shroud segments and a set of second shroud segments integrally formed on opposed surfaces of each fan blade and in substantially perpendicular relation thereto, said set of first shroud segments and said set of second shroud segments being radially spaced from one another and positioned on each said fan blade to delimit said exhaust-gas guiding fin member from said auxiliary tin member and respectively connected to sets of first and second shroud seg ments on adjacent fan blades to form therewith first and second rings defining a passage for flow of high temperature fluids, burner means for producing hightemperature fluid gases, and nozzle means disposed adjacent to said burner means for supplying said hightemperature fluid gases from said burner means to a predetermined circumferential portion of the passage defined by said first and second rings.

2. A system according to claim 1, wherein said nozzle means comprise a plurality of nozzles.

3. A system according to claim 1, wherein said nozzle means comprises a single nozzle.

4. A system according to claim 1, wherein said nozzle means comprise nozzle guide vanes, each formed with a plurality of passages for cooling of the vanes by circulating fluid.

5. A system according to claim 4, wherein the nozzle guide vanes comprise cooling fins.

6. A system according to claim 1, wherein'said disc is journalled for rotation on a shaft.

7. A system according to claim 1 in combination with a V/STOL aircraft, said system being installed in a horizontal section of the wing of the aircraft, and means for introducing bleed air, and/or exhaust gas to said burner means through the intermediary of valve means. 

1. An aerodynamic engine system comprising a lift fan assembly having a rotatable disc, a plurality of fan blades, each constituted of an inner fan blade portion and an integral outer turbo-fan blade portion, said plurality of blades being connected at their inner ends to said disc and being radially outwardly directed therefrom, each of said fan blades being gradually twisted from its inner to its outer end and being provided with a notch in the turbo-fan blade portion for forming a nozzle exhaust-gas guiding fin member and an auxiliary fin member, a set of first shroud segments and a set of second shroud segments integrally formed on opposed surfaces of each fan blade and in substantially perpendicular relation thereto, said set of first shroud segments and said set of second shroud segments being radially spaced from one another and positioned on each said fan blade to delimit said exhaust-gas guiding fin member from said auxiliary fin member and respectively connected to sets of first and second shroud segments on adjacent fan blades to form therewith first and second rings defining a passage for flow of high temperature fluids, burner means for producing hightemperature fluid gases, and nozzle means disposed adjacent to said burner means for supplying said high-temperature fluid gases from said burner means to a predetermined circumferential portion of the passage defined by said first and second rings.
 2. A system according to claim 1, wherein said nozzle means comprise a plurality of nozzles.
 3. A system according to claim 1, wherein said nozzle means comprises a single nozzle.
 4. A system according to cLaim 1, wherein said nozzle means comprise nozzle guide vanes, each formed with a plurality of passages for cooling of the vanes by circulating fluid.
 5. A system according to claim 4, wherein the nozzle guide vanes comprise cooling fins.
 6. A system according to claim 1, wherein said disc is journalled for rotation on a shaft.
 7. A system according to claim 1 in combination with a V/STOL aircraft, said system being installed in a horizontal section of the wing of the aircraft, and means for introducing bleed air, and/or exhaust gas to said burner means through the intermediary of valve means. 